The present invention is generally related to winding machines, and, more particularly, to winding machine and techniques that allow for improved shielding relative to debris, such as may be prevalent during a winding operation.
One known technique of winding, as may be performed by an exemplary winding machine 8 seen in FIG. 1, uses a strand of wire 10 that may be pulled by a rotating receiving spool or bobbin 12, with the strand of wire being fed from above the receiving spool. FIG. 1 is collectively made up of the elevational view of machine 8 illustrated in FIG. 1A and the side view illustrated in FIG. 1B. The strand of wire may be routed from a supply spool of wire (not shown) through a tensioning device 14, and down through a feed tube (e.g., wire guide) to be directed to the bobbin 12 to be wound. The wire guide acts to route the wire to a desired position during the winding of bobbin 12 with the tension device designed to provide an appropriate level of resistance to allow the wire to be properly placed and packed.
A major long term warranty issue particularly with the winding of relatively fine wire gauge (e.g., approximately 40 AWG and smaller diameter) is the presence of small pieces of wire or any other debris that may be undesirably introduced during a winding operation into, under, or on any wound device, such as the windings of an ignition coil, as may be used for automotive applications.
One common source of these small pieces of wire occurs due to operational incidents, such as the breaking or running out of wire during a high speed winding operation. When this occurs, the end of the wire on the bobbin may be rotated at a relatively high speed, breaking off into several small pieces that are then thrown around the interior of the machine, occasionally landing on an adjacent winding device. FIG. 2 illustrates exemplary paths, represented by respective dashed lines 22 and 24, of wire debris in the event of a wire breaking incident in a bobbin 122. It will be appreciated from FIG. 2 that the shielding arrangement collectively provided by respective shields 20 is unable to prevent the undesirable introduction of debris into adjacent winding assemblies 301 and 302. If these pieces are wound into, under, or statically adhere to the outside of the devices being wound, such as bobbins 121 and 123, these devices may prematurely fail in the field and be returned as warranty failures. Because of the large number of devices that may be deployed in the field, suppliers of automotive components, such as the assignee of the present invention, are particularly interested in being able to reduce or eliminate the foregoing issues without introducing burdensome costs and complicated equipment to the winding operations.
Various devices have been proposed with the intention of helping contain or prevent the introduction of debris into the wound device. Examples of such devices include protective shields that may partially surround the device being wound. The shields, as shown in FIGS. 1 and 2, generally provide a closed bottom and include openings or slits in the top to allow the wire to enter from above. Other proposed devices may include automated counters that, in theory, should prevent the wire from running out, and thus avoid the possibility of having to scrap all of the wound devices that may be simultaneously processed by any given machine, in the event of a wire break/run-out.
Unfortunately, these proposed devices are limited in their effectiveness due to their inability to properly account for the relevant physical principles applicable to the winding operation and/or cost restrictions. For example, having to scrap all parts would incrementally add cost to the winding operation since it would result in the disposal of good parts. In practice, the automated counters may not consistently prevent the occasional wire break that may occur during the winding operation. In practice, as discussed in the context of FIG. 2, the protective shields can allow stray wire and other contaminants to be pulled by gravity into the part. If a stray wire or contaminant gets “inside” one of these shields with a closed bottom, the shield unfortunately acts as a storage device and would hold the fine wire debris or contaminant undesirably close to the wound component. Elimination of the potential contaminant would require visual detection of the fine debris and burdensome manual removal, otherwise the debris may be eventually picked up due to whirling air currents that may develop inside the shield, as the receiving spool rotates and the debris could be eventually wound into the device.
In view of the foregoing considerations, it is desirable to provide low-cost and reliable winding machine and method that provides improved shielding relative to debris that may develop during a winding operation to avoid or substantially reduce the introduction of that debris into devices that, for example, may be wound simultaneously.